DMPK and myotonic dystrophy type 2: Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are multisystemic microsatellite expansion disorders caused by an expanded CTG tract in the 3' UTR of the dystrophia myotonica-protein kinase gene (DMPK) and an expanded CCTG tract in the first intron of the CCHC-type zinc finger, nucleic acid binding protein gene (CNBP, also known as ZNF9), respectively [113,114,115,116,117,118].